1. Field of the Invention
The present invention relates to an apparatus mounted on a movable body unit which, in order to enable, for example, the movable body unit to approximate to a target, can estimate the position of the target and guide the movable body unit relative to the target and a method for estimating the position of a target.
2. Description of the Related Art
In recent times, a system has been developed so as to recover an object or objects left or thrown away by an unmanned space vehicle in the outer space. In order to enable a space vehicle which cannot be operated directly by an operator to be guided toward a target or object to be recovered, it is absolutely necessary that the target position be detected.
However, no effective means has been found available up to this day, except for a now available radar system's range finding function as will be set forth below. According to the radar system, it is possible to, like other space vehicles or crafts, radiate an electromagnetic wave to the target, to receive an echo, to measure required angle and time information and to find a target's position from a result of measurement. In the radar system currently relied upon, however, a large antenna needs to be mounted outside the space vehicle, dissipating a greater electric power for electromagnetic wave radiation. It is not suitable to a space vehicle calling for a compact, lightweight and low dissipation power unit.
This problem occurs not only in a rendezvous approach guidance of the space vehicle to the target but also in the approach guidance of a movable body unit to a regularly moving target, so long as the radar system is concerned.